Vibratory screen



April 16, 196s Filed Jan. s, i964 5 Sheets-Sheet 2 April 16, 1968 A, WEHNER VIBRATORY SCREEN 5 Sheets-Sheet 3 Filed `Jan. 5, 1964 April 16, 1968v A. WEHNER VIBRATOBY SCREEN 5 Sheets-Sheet 4 Filed Jan. 5, 1964 April 16, 1968 A. WEHNER 3,378,142

, VIBRATORY SCREEN Filed Jan. 3, 1964 5 Sheets-Sheet 5 United States Patent O 16 claims. (611209-325) This invention is concerned with vibratory sieves and conveyors which operate with arcuate oscillators with sharp reversals, through the action of two oscillatory drive systems. The term screen will be used generically to include members which either function purely as a sieve or conveying member, or serve both functions.

In known apparatus of the kind specified, the screen or an intermediate frame bearing the screen has guides in which drive members of one of the driving systems so engage slidingly that the surface of the screen participates in the vibratory motion of the drive system but is so acted on during some of phases of the oscillation by the crossbearers or bearing section members associated with lthe other drive system as to move relatively to the driving members of the first-mentioned drive system. The screen can therefore perform arcuate oscillations with sharp reversals, more particularly in the form of semicircular or part-circular arcs, of a semi-circle or pant-circle or of a sickle, in a manner which is very useful for many sieving operations, more particularly for materials which are difficult to sieve. A Idisadvantage of the known screens is that the drive systems required for them are relatively complex and there is at least intermittently considerable sliding friction between the engaging parts of the screen and its drive systems, the sliding friction causing heavy wear and therefore leading to the particular elements concerned having a short working life. t

According to the present invention, to obviate these disadvantages, the drive systems are so moved and are so connected to the screen that there is complete or substantially complete synchronism in movement between the screen and the members which bear and drive it, with phase displacement during the respective bearing and driving phase of the two bearing and driving members. Sliding friction between the screen and its drive systems is therefore reduced considerably, with a corresponding considerable increase in the life.

Advantageously, the drive systems for the screen comprise two drivingly coupled resiliently borne oscillating frames having alternative inter-engaging cross-bearers which raise the screen, one such frame (namely the primary oscillating frame) being permanently coupled via appropriate drive-transmitting means with the screen or with an intermediate frame bearing the screen, so that the primary frame can, as well as transmitting the horizontal component of the oscillation throughout the whole cycle, transmit the vertical component of the oscillation to the screen in the first half of the cycle. The function of the other or secondary oscillating frame is to reduce or eliminate the vertical component of the oscillation during the second half of the cycle.

According to the invention, to provide a very simple and very reliable sieve or conveyor, the two oscillating frames perform oscillatory motions of opposite hands; advantageously, the two oscillating frames are resiliently borne by a common main frame and are driven by eccentrics which rotate in opposite directions, the eccentrics being staggered in phase relatively to one another. Conveniently, the two eccentric drive shafts are parallel to one another and pass through the centres of gravity of the respective oscillating frames which they drive. The eccentric drive shafts are directly interconnected through the agency of gears or similar drive-transmitting elements ice disposed on them and are adapted to be driven by a common electric motor or the like. The eccentrics are so staggered by 180 or some other angle in their highest or lowest positions relatively to one another that the screen performs a part-circular oscillation which has a mean direction which is either substantially in the same direction as the surface of the screen, or is at an inclination to the screen.

According to another feature of the invention, the primary oscillating frame is driven by a vibrating eccentric drive, while the secondary oscillating frame performs, with its cross-bearers engaging between the cross-bearers of the primary frame, merely a substantially horizontal motion. The secondary oscillating frame receives its horizontal motion via the screen which rests on its crossbearers in phases. Preferably, however, the secondary oscillating frame receives its horizontal motion via horizontal links, connecting springs or the like disposed between the secondary frame and the primary frame; advantageously, in this event the secondary oscillating frame is borne with the interposition of vertical rocking supportse. g. in the form of spring strips or the like.

According to the invention, as an alternative way of providing the required synchronism in movement between the screen and the driving system cross-bearers which engage therewith with phase displacement during the bearing and driving phase, the primary and secondary oscillating frames oscillate to the same hand as one another with phase dispacement, and are connected via vertical slider elements to the screen, the slider elements of the secondary oscillating frame being secured thereto -by way of resilient support members with horizontal resilience. The horizontally resilient connection between the screen and the secondary frame again prevents any sliding friction in the horizontal plane between those parts of the machine which are performing out-of-phase oscillations.

Instead of a common drive being used for the primary frame and the secondary frame, separate drives adapted to one another can be used to produce the synchronism of movement between the screen and the cross-bearers of the secondary frame which engage with the screen during the bearing or driving phase.

Examples of systems according to this invention are shown diagrammatically in the accompanying drawings. In these drawings:

FIGURES l and 2 are a side elevation and plan View respectively of a screen having oscillating frames driven via two eccentrics rotating in opposite directions;

FIGURE 3 is a motion diagram showing various phases in the oscillations occurring in the screen illustrated in FIGURES l and 2;

FIGURES 4 to 6 are a side elevation, end elevation and plan view respectively of an exampie wherein the secondary oscillating frame performs merely a horizontal motion imparted to it by the screen;

-FIGURE 7 is an end view of the machine illustrated in FIGURES 4 to 6, but in double-deck form;

FIGURES 8 and 9 are a side elevation 'and end elevation respectively of another example, the secondary oscillating frame performing a substantiallyl horizontal movement imparted to it by the primary oscillating frame, and

FIGURE lO illustrates an example having another way of driving the screen through the agency of two drive systems rotating to the same hand.

The screen illustrated in FIGURES l and 2 mainly comprises a primary oscillating frame 1 and a secondary oscillating frame 2 having :alternately operating crossbearers 3, i respectively bearing a screen 10. Each of the two frames 1, 2 is borne with :the interposition of springs 7, 7' and 8, 8 respectively by a common main frame G which rests on the machine 'bed through damping springs 9, 9'. Disposed parallel and adjacent to one another on the main fra-me G are two eccentric drive shafts 5, 6 which are directly interconnected by gears 5', 6 on them and which are driven in opposite direc-tions by a common electric motor M and a V-belt K. Each shaft 5, 6 passes through the centre of gravity of the frame 1 or 2 which it drives. The primary frame 1 is set into a circular oscillatory motion through the agency of eccentrics 11 on the shaft 5; similarly, the secondary frame 2 is set into circular oscillating motions by eccentrics 12 on the shaft 6. The cross-members 4 of the secondary frame 2 merely support the screen non-positively, but some of the cross-bearers 3 of the primary frame 1 have driving pins 13 each having an axially moving thrust plate 14 which is acted upon by a spring 14 and which tends to keep the screen 10 in engagement with corresponding cross-bearers 3. The pins 13 ensure that the horizontal component of the oscillations of the primary frame 1 is fully transmitted to the screen 10, whereas only part of the vertical component of the oscillation of the primary frame is so transmitted, namely, in the upper half-phase of the oscillations of the frame 1. In lthe example illustrated in FIG- URES 1 `and 2, the eccentrics 11, 12 on the shafts 5, 6 are staggered by 180 relatively to one another in their top and bottom positions. Consequently, the screen 19 is lifted alternately by the cross-bearers 3, 4 of the primary frame 1 and secondary fra-me 2 respectively, the sere-en 10 remaining in permanent driving engagement with the primary frame 1 so far as the horizontal component of the oscillatio-n is concerned. The screen 10 therefore performs an arcuate oscillation with sharp reversals in the form of a part-circular arc, in the manner illustrated by the curved double arrow above FIGURE 1.

The motions referred to are explained in the top row A of the motion diagram illustrated in FIGURE 3, where individual sections a, b, c, d, e denote the various phases of oscillation of the eccentrics 11, 12 with a 90 displacement between adjacent sections; the directions in which the eccentrics and the associated frames move are indicated'by arrows. The double arrows in the top line represent the force vectors which the eccentricities of the eccentrics apply to the main frame G.

The bottom row B in FIGURE 3 shows the corresponding motion and force relationships for the case where the eccentrics 11, 12 are `offset by 135 to one another, so that the oscillation of the screen 10 alters in form and in its position relatively to the plane of the screen; i.e. the oscillation becomes inclined to that plane. The force diagrams given, and the curved single arrows denoting the motion of the various oscillating frames, make this fact clear. Of course, part-circular oscillations of other magnitudes and positions can be provided by different offsetting of Ithe eccentrics 11, 12.

In the example illustrated in FIGURES 4 to 6, the primary frame 1 is driven by a vibratory out-of-balance drive 5". The primary frame 1 is borne by the machine bed with the interposition of springs 7 and cushioning elements 9, whereas the secondary frame 2 rests on the machine bed with the interposition of springs 8. In this example, the secondary frame 2 is not in `driving engagement with the primary frame 1; instead, the secondary frame 2 is so mounted through the agency of its springs 8 for resilient horizontal movement as to be adapted to perform a horizontal movement whenever the screen starts to settle on the secondary frame cross-bearers 4 at t-he descent of the primary frame cross-bearers 3. The screen therefore performs a semi-circular or partcircular oscillation of the kind illustrated by the arrows above FIGURE 4. Instead of an unbalance drive, an appropriate eccentric drive can be used. The driving motor (not shown) can be mounted directly between the side uprights of the primary frame 1 or can be connected to the eccentric shaft via V-belts. The screen which rests alternately on the cross-bearers 3, 4 has not been shown in this embodiment in order not to overcomplicate the drawings.

FIGURE 7 is an end elevation, corresponding to FIG- `UR'E 5l, of the embodiment just described, except that the screen is a double-deck apparatusie it has two screening members which are disposed at an appropriate distance one above another and which are driven by the primary and secondary frame cross-bearers 3, 4. Top deck operation is possible just with the screening member connected to one oscillating frame, in which case the top screening member performs a conventional oscillation, such as a circular, oscillation, while the bottom screening member dealing with the heavier screening can perform oscillations with sharp reversals.

In the example illustrated in FIGURES 8 and 9, the primary frame 1 has circular oscillations imparted to it by a vibratory unbalance drive or by an eccentric drive 5. The secondary frame 2 performs substantially merely a horizontal oscillation, as a result of being coupled by a horizontal link 15 with the primary frame 1. Link springs 16 which bear the secondary frame 2 ensure that the secondary frame 2 performs the substantially horizontal 0scillation as shown by the double arrow. The screen (not shown) describes the sickle-shaped motion shown above in FIGURE 8. As FIGURE 9 shows, the unbalanced shaft 5 can be covered by a protective tube 17 which bridges the two side uprights of the primary frame.

In the example illustrated in FIGURE l0, the primary frame 1 and the secondary frame 2 perform phase-displaced circular oscillation in the same direction of rotation, for instance, motions as produced by means of the rotating eccentrics 11', 12. Some of the cross-bearers 3 of the primary frame 1 having driving pins 13 which are permanently coupled with the screen 10 horizontally (Le. which produce the horizontal components of the oscillation of the screen). A slider 18 is mounted for axial displacement on the pin 13 and is clamped by a cap nut 19 against a reinforcing ring 20 on the screen 10. This ensures that there can be a vertical sliding movement between the pin 13 and the member 10 in the manner required for the production, according to the invention, of arcuate oscillations of the screen 10 with sharp reversals. The secondary frame cross-bearers 4 also have driving -pins 13 which extend through the member 10 and are connected thereto for vertical sliding just like the pins 13 of the primary frame 1. Unlike the latter, however, the pins 13 are not rigid but are connected by resilient support members 21 to the secondary frame cross-bearers 4 so as to be adapted to perform, in the manner illustrated in FIGURE 10, a horizontal movement relatively to the cross-bearers 4. The support members 21, which can be, for instance, of rubber, experience shear stressing. Consequently, although the eccentrics 11', 12 rotate in the same direction, the oscillations of the frames impart to the screen 10 arcuate oscilla-tions with sharp reversals without any sliding occurring during the horizontal movement between the screen 10 and the secondary frame 2. This kind of drive for the screen 10 is very suitable for the supply of electricity to heat the screen.

This invention can be embodied and varied in a wide variety of ways. For instance, the primary frame 1 can have side uprights forming screen box walls, and some of its cross-connections can be supply and delivery chutes below which the bearing springs 7, 7 of the primary frame 1 are disposed, as shown by way of example in FIGURE 1. Also, because of the dynamic conditions in the two phases of motion of the sharply reversing arcuate oscillations, it is very advantageous in the case of a conveyor (particularly if the screen is inclined) for the primary frame 1 to describe the arc from the discharge side towards the supply sideie during the time when the screen 10 is supported by the primary frame crossbearers 3. On the other hand, it is best for the secondary frame 2 to produce the arc from the supply side to the discharge side, since the inertia of the material being conveyed (and sieved), and of the screen 10', can then have good use made of them-ie. there is reduced stressing of the bearing structure of the machine. In other words, the drive direction of the frames 1, 2 is preferably such that the screen 10 performs its larger arc in the opposite direction to the direction in which the material is being conveyed.

Advantageously, the s-creen can be used to form the bottom closure of a bunker for loose-fill material, or of a similar receptacle. Also, the bearing elements (i.e., the cross-bearers 3, 4) of the two oppositely moving frames 1, 2 can be so devised as to be parts of the screen elements of a double-screen lattice. The screen can also be formed as a multiple-deck screen, in whichevent, in addition to the screen which is driven by the primary and secondary oscillating frames and which performs arcuate oscillations with sharp reversals, one or more additional screens performing the same or diierent forms of oscillation can be disposed at appropriate intervals one above another.

I claim:

1. Vibratory screen assembly comprising two oscillatory driving systems, each having a resiliently supported frame and a set of support members on said frame, a screen supported on both of said sets of support members, means for impartinga rotary oscillation cycle to at least one of said oscillatory driving systems, means connecting said one oscillatory driving system to said screen for transmitting the upper part of the rotary oscillation cycle from said one oscillatory driving system to said screen, said connecting means forming a positive entrainment for said screen in a substantially horizontal direction and said screen being displaceable upwardly relative to said latter connecting means, the set of support members of said one oscillatory driving system being adapted to raise said screen from the set of support members of the other oscillatory driving system during the period in which the upper part of the rotary oscillation cycle is transmitted to said screen and to lower said screen so that it is supported by the set of support members of the other oscillatory driving system during the period in which said one oscillatory driving system performs the lower part of the rotary oscillation cycle, said two oscillatory systems with their respective support members having the same direction of their horizontal component of oscillation during the lower part of the screen oscillation cycle, whereby said screen is moved horizontally in substantial synchronism with both of said sets of support members during said lower part of said cycle.

2. Vibratory screen assembly according to claim 1, wherein said means for imparting a rotary oscillation cycle Iare adapted to impart circular oscillatory motion to said pair of oscillating frames in opposite rotary directions.

3. Vibratory screen assembly according to claim 2, including a common main frame resiliently supporting said pair of oscillating frames, said means for imparting oscillatory motion to said pair of oscillating frames comprising a pair of oppositely rotatable eccentrics mounted on said common main frame.

4. Vibratory screen assembly according to claim 3, wherein said eccentrics are staggered substantially 180 from one another.

5. Vibratory screen assembly according to claim 3, including a machine bed resiliently supporting said main frame.

6. Vibratory screen assembly according to claim 3, wherein each of said eccentrics is mounted on a drive shaft extending parallel to the other and passing respectively through the centers of gravity of said oscillating frames.

7. Vibratory screen assembly according to claim 6,

including gear means for operatively interconnecting said eccentric drive shafts directly, and a single motor connected to one of said eccentric shafts for driving both of said eccentrics in common.

8. Vibratory screen assembly according to claim 1, wherein said means for imparting a rotary oscillation cycle to said one oscillatory driving system comprises a vibrating eccentric drive, said other oscillatory driving system being engageable by said screen for imparting an oscillation thereto in a substantially horizontal direction.

9. Vibratory screen assembly according to claim 1, comprising at least one substantially horizontal link connecting said frame of said one oscillating driving System with said frame of said other oscillating driving system, said latter frame being oscillatable in said substantially horizontal direction by said frame of said one oscillating driving system through said link.

10. Vibratory screen assembly according to claim 9, including substantially vertical rocking supports for the oscillating frame of said other oscillating driving system.

11. In a vibratory screen assembly according to claim 1, said frames of said oscillating driving systems being oscillatable in the same direction out of phase with one another, and including substantially vertical slider means for connecting said frames to said screen, the frame of said other oscillating driving system having the respective vertical slider means secured thereto by support members resilient in a substantially horizontal direction.

12. In a vibratory screen assembly according to claim 1, said frame of said one oscillating driving system having lateral upright walls forming a screen box, a cross-connection for said walls in the form of a supply and delivery chute, and spring means for supporting the oscillating frame of said one oscillating driving system below said chute.

13. Vibratory screen assembly according to claim 1, including a receptacle for a loose ll material, said screen forming a bottom closure for said receptacle.

14. In a vibratory screen assembly according to claim 1, said means for imparting a rotary oscillation cycle being adapted to impart circular oscillatory motion to said pair of oscillating frames in opposite rotary directions, the support members of said sets of support members for said oscillatory driving systems being alternately interengaging so as to form a double-screen lattice.

15. In a vibratory screen assembly according to claim 1, said screen, said oscillating frames and said support members consisting at least in part of electrically conductive material for supplying an electric current to heat said screen.

16. Vibratory screen assembly according to claim 1, including at least one additional screen oscillatable in a similar manner as said first-mentioned screen, said addiltional screen being located above and. spaced from said irst-mentioned screen.

References Cited UNITED STATES PATENTS 894,424 7/ 1908 Converse 209-396 X 1,131,478 3/1915 Custer 209-347 1,961,534 6/ 1934 'Symons 209-365 X 2,825,461 3/1958 Hannon 209-238 2,901,110 8/1959 Brumagin 209-3 65 X 3,217,881 11/1965 Wehner 209-330 3,261,469 7/1966 Wehner 209-396 X FOREIGN PATENTS 1,179,805 12/1958 France. 1,282,300 12/1961 France.

900,704 7/ 1962 Great Britain.

HARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner. 

1. VIBRATORY SCREEN ASSEMBLY COMPRISING TWO OSCILLATORY DRIVING SYSTEMS, EACH HAVING A RESILIENTLY SUPPORTED FRAME AND A SET OF SUPPORT MEMBERS ON SAID FRAME, A SCREEN SUPPORTED ON BOTH OF SAID SETS OF SUPPORT MEMBERS, MEANS FOR IMPARTING A ROTARY OSCILLATION CYCLE TO AT LEAST ONE OF SAID OSCILLATORY DRIVING SYSTEMS, MEANS CONNECTING SAID ONE OSCILLATORY DRIVING SYSTEM TO SAID SCREEN FOR TRANSMITTING THE UPPER PART OF THE ROTARY OSCILLATION CYCLE FROM SAID ONE OSCILLATORY DRIVING SYSTEM TO SAID SCREEN, SAID CONNECTING MEANS FORMING A POSITIVE ENTRAINMENT FOR SAID SCREEN IN A SUBSTANTIALLY HORIZONTAL DIRECTION AND SAID SCREEN BEING DISPLACEABLE UPWARDLY RELATIVE TO SAID LATTER CONNECTING MEANS, THE SET OF SUPPORT MEMBERS OF SAID ONE OSCILLATORY DRIVING SYSTEM BEING ADAPTED TO RAISE SAID SCREEN FROM THE SET OF SUPPORT MEMBERS OF THE OTHER OSCILLATORY DRIVING SYSTEM DURING THE PERIOD IN WHICH THE UPPER PART OF THE ROTARY OSCILLATION CYCLE IS TRANSMITTED TO SAID SCREEN AND TO LOWER SAID SCREEN SO THAT IT IS SUPPORTED BY THE SET OF SUPPORT MEMBERS OF THE OTHER OSCILLATORY DRIVING SYSTEM DURING THE PERIOD IN WHICH SAID ONE OSCILLATORY DRIVING SYSTEM PERFORMS THE LOWER PART OF THE ROTARY OSCILLATION CYCLE, SAID TWO OSCILLATORY SYSTEMS WITH THEIR RESPECTIVE SUPPORT MEMBERS HAVING THE SAME DIRECTION OF THEIR HORIZONTAL COMPONENT OF OSCILLATION DURING THE LOWER PART OF THE SCREEN OSCILLATION CYCLE, WHEREBY SAID SCREEN IS MOVED HORIZONTALLY IN SUBSTANTIAL SYNCHRONISM WITH BOTH OF SAID SETS OF SUPPORT MEMBERS DURING SAID LOWER PART OF SAID CYCLE. 